Introduction

Data science isn't all statistical modeling, machine learning, and data frames. Eventually, your hard work pays off and you need to give back the data and the results of your analysis; those blinding insights that you and your team uncovered need to be operationalized in the final stage of the data science pipeline as a scalable data product. Fortunately for you, the web provides an equitable platform to do so and Python isn't all NumPy, Scipy, and Pandas. So, which Python web application framework should you jump into?

There are numerous web application frameworks for Python with the 800lb gorilla being Django, "the web framework for perfectionists with deadlines." Django has been around since 2005 and, as the community likes to say, is definitely "batteries included," meaning that Django comes with a large number of bundled components (i.e., decisions that have already been made for you). Django comes built in with its chosen object-relational mapper (ORM) to make database access simple, a beautiful admin interface, a template system, a cache system for improving site performance, internationalization support, and much more. As a result, Django has a lot of moving parts and can feel large, especially for beginners. This behind the scene magic can obscure what actually happens and complicates matter when something goes wrong. From a learning perspective, this can make gaining a deeper understanding of web development more challenging.

Enter Flask, the micro web framework written in Python by Armin Ronacher. Purportedly, it came out as an April Fool's joke but proved popular enough not to go quietly into the night. The incredible thing about Flask is that you can have a web application running in about 10 lines of code and a few minutes of effort. Despite this, Flask can and does run real production sites.

As you need additional functionality, you can add it through the numerous extensions available. Need an admin interface? Try Flask-Admin. Need user session management and the ability for visitors to log in and out? Check out Flask-Login.

While Django advocates may argue that by the time you add all of the "needed" extensions to Flask, you get Django, others would argue that a micro-framework is the ideal platform to learn web development. Not only does the small size make it easier for you to get your head around it at first, but the fact that you need to add each component yourself requires you to understand fully the moving parts involved. Finally, and very relevant to data scientists, Flask is quite popular for building RESTful web services and creating APIs.

As Flask documentation isn't quite as extensive as the numerous Django articles on the web, I wanted to assemble the materials that I have been looking at as I explore the world of Flask development.

For Beginners - Getting Started

The Official Flask Docs

The official Flask home page has a great set of documentation, list of extensions to add functionality, and even a tutorial to build a micro blogging site. Check it out here.

Blog post on Learning Flask

This tutorial is really a hidden gem designed for those that are new to web programming and Flask. It contains lots of small insights into the process via examples that really help connect the dots.

Full Stack Python

While not exclusively focused on Flask, Fullstackpython.com is a fantastic page that offers a great amount of information and links about the full web stack, from servers, operating systems, and databases to configuration management, source control, and web analytics, all from the perspective of Python. A must read through for those new to web development.

Starting A Python Project the Right Way

For Intermediate Developers

The Flask Mega Tutorial

The Flask Mega Tutorial is aptly named as it has eighteen separate parts walking you through the numerous aspects of building a website with Flask and various extensions. I think this tutorial is pretty good but have heard some comment that it can be a bit much if you don't have a strong background in web development.

Miguel Grinberg's tutorial has been so popular that it is even being used as the basis of an O'Reilly book, Flask Web Development, that is due out on May 25, 2014. An early release is currently available, so called "Raw & Unedited," here.

A snippet about the book is below:

If you have Python experience, and want to learn advanced web development techniques with the Flask micro-framework, this practical book takes you step-by-step through the development of a real-world project. It’s an ideal way to learn Flask from the ground up without the steep learning curve. The author starts with installation and brings you to more complicated topics such as database migrations, caching, and complex database relationships.

Each chapter in this focuses on a specific aspect of the project—first by exploring background on the topic itself, and then by waking you through a hands-on implementation. Once you understand the basics of Flask development, you can refer back to individual chapters to reinforce your grasp of the framework.

Flask Web Development

Flask - Blog: Building a Flask Blog: Part1

This blog contains two different tutorials in separate posts. This one, tackles the familiar task of building a blog using Flask-SQLAlchemy, WTForms, Flask-WTF, Flask-Migrate, WebHelpers, and PostgreSQL. The second one shows the creation of a music streaming app.

Flask with uWSGI + Nginx

Python Web Applications with Flask

This extensive 3 part blog post from Real Python works its way through the development of a mid-sized web analytics application. The tutorial was last updated November 17th of 2013 and has the added bonus of demonstrating the use of virtualenv and git hub as well.

Python and Flask are Ridiculously Powerful

Jeff Knupp, author of Idiomatic Python, is fed up with online credit card payment processors so builds his own with Flask in a few hours.

More Advanced Content

The Blog of Erik Taubeneck

This is the blog of Erick Taubeneck, "a mathematician/economist/statistician by schooling, a data scientist by trade, and a python hacker by night." He is a Hacker School alum in NYC and contributor to a number of Flask extensions (and an all around good guy).

How to Structure Flask Applications

Here is a great post, recommended by Erik, discussing how one seasoned developers structures his flask applications.

This 68-slide presentation on Flask from Devert Alexandre is an excellent resource and tutorial discussing Flask, the very popular SQL Alchemy and practically default Flask ORM, and the Jinja2 template language.

Diving Into Flask - Presentation

A 66-slide presentation on Flask
by Andrii V. Mishkovskyi from EuroPython 2012 that also discusses Flask-Cache, Flask-Celery, and blueprints for structuring larger applications.